Evolution of a Software-Defined Radio Receiver's RF Front-End

The subject of this paper is how to construct this flexible receiver. We survey the steps that have been taken over the years in this direction - some very tenuously - leading up to a recent realization of a software-defined RF front-end. We do not cover the work that has gone into the digital front-end which follows the ADC (Hentschel and Fettweis, 2002), nor on the software-defined baseband - both are essential for a full radio. Furthermore, an efficient software-defined transmitter without which the software-defined radio project is incomplete is still in the research phase